The present invention relates to a method and apparatus for treating or manipulating plate-like workpieces, and more particularly to improvements in a method and apparatus for trimming plate-like bodies which consist of or comprise two or more overlapping layers or strata. Typical examples of such workpieces are laminates wherein a centrally located layer of wood is flanked by outer layers consisting of wood or synthethic plastic material.
Trimming of laminated workpieces presents no serious problems as long as each of the layers is readily accessible so that the workpiece can be properly positioned with reference to one or more rotary circular saws and/or other suitable trimming or severing instrumentalities. However, when one or both outer layers project laterally beyond the layer or layers therebetween and the position of a median layer is controlling for a satisfactory trimming operation, presently known trimming apparatus are incapable of ensuring adequate and reproducible positioning of each of a series of raw (untrimmed) workpieces with respect to the cutting tool or tools. Accurate trimming is often desirable and/or necessary, for example, when the finished workpieces are to be used as component parts of fine furniture or the like. On the other hand, the configuration of laminated workpieces which issue from a press wherein the neighboring layers are bonded to each other in response to the application of heat, pressure and/or adhesive is often highly irregular, and it happens again and again that the outer layers extend well beyond the layer or layers therebetween. In many instances, the median layer or layers are fully concealed by both outer layers so that the edge face or faces of the median layer or layers are neither visible nor readily accessible. As a rule, the workpieces are trimmed in apparatus which employ a rotary circular saw and a feeding means which can engage a freshly admitted workpiece and moves the workpiece between several positions in accordance with a preselected program. Apparatus of the just outlined character can further comprise a pressure applying beam for the workpiece (or a stack of workpieces) and means for driving the circular saw as well as for moving the saw so that the axis of the saw is located at a level below the feeding means. Reference may be had to the commonly owned copending patent application Ser. No. 115,880 filed Jan. 28, 1980, now abandoned. Such automatic apparatus cannot be used for rapid trimming of a short or long series of workpieces wherein the median layer or layers are not readily accessible if the marginal portions or edge faces of the median layer or layers are to be used as reference points for initial positioning of a workpiece before the programming unit for the work feeding means takes over and moves the workpiece to one or more preselected positions with reference to the trimming plane.